Cisco Broadband Cable Command Reference Guide

show controllers clock-reference
show controllers clock-reference
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Cisco Broadband Cable Command Reference Guide
Chapter 2 Cisco Cable Modem Termination System Commands
To display hardware information, register values, and current counters for the TCC+ card or the
Cisco cable clock card, use the show controllers clock-reference command in privileged EXEC mode.
show controllers clock-reference
Syntax Description This command has no keywords or arguments.
Command Modes Privileged EXEC
Command History
Release Modification
12.1(1a)T1 This command was introduced.
12.1(2)EC1 This command was supported on the EC train.
12.2(2)XF This command was supported for the TCC+ card on Cisco uBR10012
routers.
12.2(4)BC1 Support was added to the Release 12.2 BC train.
Usage Guidelines To reset the counters that are displayed with the show controllers clock-reference command, use the
cable clock clear-counters command.
Note This command is not applicable on the SC train.
This command supports the Cisco CMTS clock feature set, which provides a synchronized clock for
improved Voice-over-IP (VoIP) operations. The clock feature set requires one of the following
configurations:
A Cisco uBR10012 router with one or two TCC+ cards that are connected to an external national
clock source.
A Cisco uBR7246 VXR router using a Cisco uBR-MC16S, Cisco uBR-MC16E,
Cisco uBR-MC28C, or Cisco uBR-MC28C-BNC cable interface line card. The router must also be
equipped with a Cisco cable clock card and be running Cisco IOS 12.1(1a)T1, 12.1(2)EC1, or a later
release. The Cisco cable clock card should be connected to an external national clock source.
Only these cable interface cards support the external clock card reference from a clock card to distribute
that signal to CMs or set-top boxes (STBs) attached to the specific network segments. You can use other
cable interface cards, such as the Cisco uBR-MC16C, with the clock card, but these other cable
interfaces will not synchronize their downstream SYNC messages with the external clock source.
Each CM or STB must also support VoIP applications and the clock feature set. For example, the
Cisco uBR924, running Cisco IOS Release 12.0(7)T or later, supports clock card feature automatically.
Examples The following is sample output from the show controllers clock-reference command for a
Cisco uBR7246 VXR router with a national clock card:
OL-1581-05